The present disclosure relates generally to maintaining multicast data flow in the event of a network failure.
Traditional Internet Protocol (IP) communication allows a host to send packets to a single host (unicast transmission) or to all hosts (broadcast transmission). To support a demand to provide applications such as audio and video conference calls, audio broadcasting, and video broadcasting that involve high data rate transmission to multiple hosts, a third routing technique has evolved, multicast routing. In multicast routing, a host sends packets to a subset of all hosts as a group transmission. Multicast routing protocols have been developed to conserve bandwidth by minimizing duplication of packets. To achieve maximum efficiency delivery of data, rather than being replicated at the source, multicast packets are replicated in a network at the point where paths to multiple receivers diverge.
Conventional multicast routing systems depend on unicast routing protocols to detect a network failure. Redirection of impacted traffic does not occur until after the network failure has been identified by the unicast routing protocol and a new path has been established. In many cases, such as video applications that require near-zero packet loss, this impacts network performance during failure recovery. One approach to overcome this performance degradation is to provide source redundancy in which separate multicast hosts are provisioned and located in the network to achieve diverse paths. However, this requires the use of multiple hosts and synchronization of data streams. Also, the source redundancy model results in a significant waste of bandwidth.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.